Al³⁺

Cr³⁺

Fe³⁺

Zn²⁺

CaO

Na₂O₂

ZnO

Mn₃O₄

Reduction to cuprous hydroxide

Complex formation

Increase in pH

The amphoteric nature of Cu(OH)₂

Chlorine is passed into aqueous KMnO₄ solution

Manganese dioxide is fused with potassium hydroxide in air

Formaldehyde reacts with potassium permanganate in presence of a strong alkali

Potassium permanganate reacts with concentrated sulphuric acid

Blue precipitate of copper hydroxide is obtained

Black precipitate of copper oxide is obtained

A deep blue solution is obtained

No change is observed